MESOSCALE DISCUSSION 2388
   NWS STORM PREDICTION CENTER NORMAN OK
   0750 AM CST THU DEC 22 2011
   
   AREAS AFFECTED...ERN LA AND SRN/CENTRAL MS
   
   CONCERNING...TORNADO WATCH 898...
   
   VALID 221350Z - 221445Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 898 CONTINUES.
   
   13Z SURFACE ANALYSIS SHOWS AN ELONGATED AREA OF LOW PRESSURE
   EXTENDING FROM E CENTRAL LA /45 WNW BTR/ INTO SRN MS /30 SSE JAN/
   WITH THE WARM FRONT STRETCHING NEWD THROUGH CENTRAL AL TO NRN GA.
   SLY LOW LEVEL FLOW S OF THIS FRONT IS CONTINUING TO DESTABILIZE THE
   WARM SECTOR DESPITE WEAK LAPSE RATES WITH MUCAPE OF 500-1000 J/KG. 
   WATER VAPOR IMAGERY SUGGESTS A LEAD IMPULSE MAY BE TRACKING NEWD
   ACROSS THE LOWER MS VALLEY ATTM AND SUPPORTING THE CONVECTIVE
   CLUSTER OVER WEST CENTRAL/CENTRAL MS AND SWD EXTENDING WIND SHIFT. 
   MEANWHILE...THE IMMEDIATELY UPSTREAM SHORTWAVE TROUGH IS BECOMING
   NEGATIVELY TILTED AS IT TRACKS INTO E TX.  INCREASING LARGE SCALE
   ASCENT AHEAD OF THIS LATTER TROUGH WILL FURTHER ENHANCE THE
   DEVELOPMENT OF TSTMS ALONG THE LEAD WIND SHIFT AND DISCRETE STORMS
   WITHIN THE WARM SECTOR.
   
   ALTHOUGH LOW LEVEL WINDS OVER CENTRAL MS ARE CALM TO NLY...DEEP
   LAYER WIND PROFILES SUGGEST THE RELATIVELY COOLER SURFACE AIR MASS
   IS NOT VERY DEEP N OF THE SURFACE LOW/WARM FRONT...WITH SLY WINDS
   JUST OFF THE SURFACE...INCREASING AND VEERING TO SWLY WITH HEIGHT. 
   A FEW DEGREE INCREASE OF SURFACE TEMPERATURE/DEW POINT IN THIS TYPE
   OF ENVIRONMENT /STRONGLY SHEARED THROUGH A DEEP LAYER AND LOWER
   LEVELS/ WILL SUPPORT AN ORGANIZED STORM PRODUCING DAMAGING WINDS
   AND/OR AN ISOLATED TORNADO.
   
   ..PETERS.. 12/22/2011
   
   
   ATTN...WFO...BMX...MOB...MEG...JAN...LIX...LCH...
   
   LAT...LON   29479253 31179157 31799078 32489057 33458953 33678940
               33778851 33568816 31848850 31138914 30158965 29208999
               28689023 28619093 29009194 29269257 29479253